EQUALITYColumn contributes to a predicate that expresses equality, of the form:table.column =constant_value

INEQUALITYColumn contributes to a predicate that expresses inequality, for example, a predicate of the form:table.column > constant_valueAny comparison operator other than "=" expresses inequality. For a complete list of comparison operators, see Comparison Operators (Database Engine).

INCLUDEColumn is not used to evaluate a predicate, but is used for another reason, for example, to cover a query.

Information returned by sys.dm_db_missing_index_columns is updated when a query is optimized by the query optimizer, and is not persisted. Missing index information is kept only until SQL Server is restarted. Database administrators should periodically make backup copies of the missing index information if they want to keep it after server recycling.

The output from the sys.dm_db_missing_index_columns dynamic management function can be used by any tool that can read the missing index information that corresponds to an index_handle, process the information, and convert it into CREATE INDEX DDL statements that implement the missing index. For more information about creating DDL statements, see Using Missing Index Information to Write CREATE INDEX Statements.

Transaction Consistency

If a transaction creates or drops a table, the rows containing missing index information about the dropped objects are removed from this dynamic management object, preserving transaction consistency. For more information about transaction consistency in relation to the missing indexes dynamic management objects, see About the Missing Indexes Feature.

The following example runs a query against the Address table and then runs a query using the sys.dm_db_missing_index_columns dynamic management view to return the table columns that are missing an index.